flow resistance parameter, \(\mathit{\Phi}\)

in chromatography
https://doi.org/10.1351/goldbook.F02444
A term used to compare packing density and permeability of columns packed with different particles; it is dimensionless. \[\mathit{\Phi} = \frac{d_{\text{p}}^{2}}{B_{0}}\] where \(d_{\text{p}}\) is the average particle diameter. In open-tubular columns \(\mathit{\Phi} = 32\).
Source:
PAC, 1993, 65, 819. 'Nomenclature for chromatography (IUPAC Recommendations 1993)' on page 833 (https://doi.org/10.1351/pac199365040819)